三种系统可靠性评估方法的比较与分析

故障树、故障Petri网和贝叶斯网络是评估系统可靠性、安全性的三种重要模型。其中,故障树在工程中应用最广,而后两种模型其各自具有不可替代的优点,可以弥补故障树在实际应用中的不足。在介绍三种模型的基础上,通过对故障树向故障Petri网转化方法、故障树向贝叶斯网络转化方法的研究,给出描述三种模型的典型逻辑关系等价结构图的表格,揭示三种模型的内在联系。结合该表,提出故障Petri网向贝叶斯网络的转化方法。同时,利用上述三种模型对导弹发动机故障进行对比分析,结果表明故障Petri网使故障传播过程一目了然,而通过故障Petri网络或故障树转化而来的等价贝叶斯网络可计算出更多定量结果。

Methods for evaluating systems based on faulty petri net and Bayesian network

Fault tree,faulty Petri net and Bayesian network are three powerful models used to assess a system＇s reliability and safety.Fault tree is the most widely used while each of the latter two has its own irreplaceable merits,which can make up fault tree＇s deficiency in practice.Based on the basic knowledge about these three models,both method for mapping fault trees into faulty Petri nets and method for mapping fault trees into Bayesian networks are discussed.Combing with these two methods stated above,a table that shows these three models＇ equivalent classic logic topology is presented,which reveals the inner connection among these three models.On the basis of the table,a method for mapping a faulty Petri net into Bayesian network is raised.Meanwhile,a failure event of unexpected ignition of an engine is studied and compared using these three models separately and the results show that faulty Petri net describes the process of fault propagation clear and using the equivalent Bayesian network that mapped from a Petri net or fault tree,more quantitative information can be calculated.